ABSTRACT
It is critical for the aeronautical industry that the next generation of smart coatings allows the early detection and continuous monitoring of corrosion. Once corrosion is detected, preventive actions can be taken in order to mitigate its costs.
Our strategy relies on functional coatings capable of detecting metallic corrosion early on. After appropriate selection of sensing compounds and subsequent loading into nanostructured materials [2], these are incorporated into coating formulations giving them corrosion sensing functionality. Based on this concept we focused on the compatibility between nanocontainers and coating formulations. Thus, a new sensing coating was investigated using immersion and salt-spray tests, release and leaching studies, viscoelastic properties, curing, thermal stability, hardness, mechanical properties and corrosion resistance. The results embody a new generation of coatings with sensing ability, and have implications for self-healing and anti-fouling coatings as well.
INTRODUCTION
Corrosion is a chemical force with an economic impact to be reckoned with. Early detection and subsequent mitigation are fundamental to minimize its costs and propel healthier economies.
Direct impregnation of pH indicators into coatings was a foundational technology that showed the potential to achieve corrosion sensing [1-3]. These functional coatings are capable of changing color when corrosion ensues and pH changes [4].
State of the art technologies rely on the use of hosting structures for detection of corrosion [5] that are able to store pH indicating molecules and release them as active components upon demand. These technologies use micro- and nanomaterials with the capacity to release sensing species upon demand following an external chemical trigger, and can be applied as functional additives for polymeric coatings imparting them self-sensing capability. The advantage of using functional additives instead of directly adding organic compounds to the coatings is to limit detrimental reactions between the compounds and the coating formulation, as well as a more localized response since only materials close to corroded sites will provide a signal.
